Certain lasers emit radiation with randomly varying polarization. This random polarization interacts with the optics that are downstream from the laser. This results in undesirable variations in the power or energy that is received at the workpiece from the laser.
The present invention is directed to an apparatus and method of reducing the effects of random polarization on the output uniformity of a laser beam. In particular, the method and apparatus measures the effects of the random polarization and compensates for the effects to produce repeatable uniform power or energy levels.
The present invention is directed to a method of and an apparatus for reducing the effects of random polarization on the output uniformity of a laser beam and includes generating a polarized laser beam, separating a fraction of the laser beam into first and second polarized components that are orthogonal to each other, and measuring the energy in each of the first and second components. The method also includes measuring the total energy in both of the first and second components and comparing the total power or energy with a predetermined set point, and thereafter controlling the power or energy output of the laser beam in response to the comparison of the output with the set point.
Another object of the present invention includes integrating the total energy prior to comparing the total energy with a predetermined set point.
Still a further object of the present invention is wherein in one embodiment the energy is controlled by turning the laser off and on and in another embodiment the energy is controlled by controlling the intensity of the laser.
Still a further object of the present invention is the provision of an apparatus for reducing the effects of random polarization by providing first and second polarizing beams splitters positioned in the polarized laser beam and positioned orthogonally to each other. The first and second beam splitters each reflect a portion of the laser beam. Laser detecting and measuring means detect and measure the reflected polarized energy from each of the beam splitters, and comparison means compares the sum of the measured energy from both of the beam splitters with a predetermined energy level. Control means between the comparator and the laser are provided for controlling the output energy of the laser.
The beam splitters may be dielectric windows and the laser detecting and measuring means may be photodiodes.
Other and further objects, features and advantages will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings.